Nothing to do with the power vacuum left by the US after destroying Iraq and Afghanistan? Nothing to do with weapons and training distributed in that region by the US many years ago? Nothing to do with drone strikes fueling anti-American sentiment that's then used as motivation and justification for performing acts of terror?

I didn't say US is the whole reason here. But it's a big part of it.

You, sir, have a lot of reading to do. I'd start with a few histories of the region, then move into political theory.

May I recommend the following?

"Afghanistan: A Cultural and Political History" by Thomas Barfield